In recent years, the development of medical X-ray CT imaging apparatuses has advanced and many apparatuses having provisions for imaging in dentistry or imaging of head including otolaryngological regions and the like have been developed and manufactured. In the field of dental X-ray CT imaging apparatus, apparatuses for combined use of not only CT imaging but also panoramic radiography (disclosed in e.g., Japanese Patent No. 3807833) have been developed. Japanese Patent Application Laid-Open Gazette No. 54-113292 discloses an example of old-type medical X-ray CT imaging apparatus which performs film radiography. The medical X-ray imaging apparatus disclosed in Japanese Patent Application Laid-Open Gazette No. 54-113292 is a dental panoramic radiography apparatus having a function of temporomandibular joint radiography, which is capable of both radiography of temporomandibular joints in open and closed states and panoramic radiography thereof. The X-ray imaging apparatus disclosed in Japanese Patent Application Laid-Open Gazette No. 54-113292, however, is not an X-ray CT imaging apparatus and therefore the apparatus cannot reconstruct the cross sections of the temporomandibular joints from an arbitrary direction.
As another example of medical X-ray CT imaging apparatus, Japanese Patent Application Laid-Open Gazette No. 2006-149446 discloses an X-ray CT imaging apparatus, which is used for diagnosis of organs located at left and right sides of a spine as a center. The X-ray CT imaging apparatus disclosed in Japanese Patent Application Laid-Open Gazette No. 2006-149446 has a technology for extracting portions which are symmetrically located at left and right sides of a spinal cord as a center line. Japanese Patent No. 3926120 discloses an apparatus for specifying a region of interest on a schematic view of a subject as an imaging target region and performing X-ray CT imaging of the imaging target region.